Understanding What Genetic Drift Is
Genetic drift is a random change in the frequency of traits within a population. Instead of traits spreading because they are useful, they shift simply by chance.
How Genetic Drift Works
In small populations, random events—like who happens to survive or reproduce—can cause certain genetic traits to become more or less common. These changes are not driven by advantage or fitness, just luck.
Examples of Genetic Drift
Two classic examples are the founder effect, where a small group starts a new population, and the bottleneck effect, where a population is sharply reduced, leaving only certain traits behind by accident.
Why Genetic Drift Matters
Genetic drift can reshape a population’s genetic makeup over generations. It explains how diversity can be lost, how isolated groups develop unique traits, and how evolution can happen without selective pressure.
Key Characteristics of Genetic Drift
• Driven by random chance, not by survival advantage.
• Stronger in small populations.
• Can increase or eliminate traits unpredictably.
• Works alongside natural selection in shaping evolution.
The Simple Takeaway
Genetic drift is evolution powered by chance. In small populations, random events can shift which traits become common, showing that not all evolutionary change comes from natural selection.